Marilyn has been married three times. There are rumours going around that she was married to Bob Slatzer for only a few days in Mexico (October 1952), but there is no marriage certificate to prove it and honestly: I don't buy it. The only pictures that exist from Slatzer and Marilyn are a few photo's taken during shooting Niagara.
There are also rumors that Marilyn and Joe DiMaggio (her 2nd husband) were supposed to get married again in 1962, but they never did. Relatives of DiMaggio say Marilyn died before they had the chance to get married.

James Dougherty (June 1942 - September 1946)

Marilyn's first husband was James Dougherty. She married him shortly after her 16th birthday, on June 19, 1942, and divorced him in September of 1946. Norma Jeane spent most of her childhood in foster homes and orphanages until 1937, when she moved in with family friend Grace McKee Goddard. Unfortunately, when Grace's husband was transferred to the East Coast in 1942, the couple couldn't afford to take 16-year-old Norma Jeane with them. Norma Jeane had two options: return to the orphanage or get married. She chose to be married.
"She was a sweet, generous and religious girl," Jimmy said. "She liked to be cuddled." By all accounts Norma Jeane loved Jimmy, and they were happy together until he joined the Merchant Marines and was sent to the South Pacific in 1944. In 1946 Marilyn divorced James to follow her career.
» click here for the invitation for the wedding

Joe DiMaggio (January 1954 - October 1954)

On January 14, 1954, Marilyn married baseball superstar Joe DiMaggio at San Francisco's City Hall. They had been a couple for two years, after Joe asked his agent to arrange a dinner date. During their Tokyo honeymoon, Marilyn took time to perform for the service men stationed in Korea. Her presence caused a near-riot among the troops, and Joe was clearly uncomfortable with thousands of men ogling his new bride.
Unfortunately, Marilyn's fame and sexual image became a theme that haunted their marriage. Nine months later on October 27, 1954, Marilyn and Joe divorced. They attributed the split to a "conflict of careers" and remained close friends.

Arthur Miller (June 1956 - January 1961)

On June 29, 1956, Marilyn wed playwright Arthur Miller. The couple met through Strasberg, and friends reported she made him "giddy." While they were married, Arthur wrote the part of Roslyn Taber in 1961's The Misfits especially for Marilyn. Sadly, the marriage between Marilyn and Arthur ended on January 20, 1961, and The Misfits was to be Marilyn's last completed film.